Organic Reactions

Jennifer Grant

Alkane Reactions: Combustion and Halogenation (Substitution with Halogens)

Alkanes have low reactivity:

  • C-C and C-H are strong bonds that aren't easily broken in reaction
  • Alkanes are non-polar because of their C-C and C-H bonds and therefore do not attract other ions or polar molecules
  • Alkanes have Van der Waal's forces
  • C1 to C4 alkanes are volatile (gaseous at room temperature)

Combustion Reactions: Complete Combustion

  • A complete combustion (has excess O2) and produces CO2 and H2O
  • A complete combustion requires some heat to get it started and a large amount of oxygen
  • Example: 2 C4H10 + 13 O2 ---> 8 CO2 + 10 H2O

Combustion of alkanes

Combustion Reactions: Incomplete Combustion

  • An incomplete combustion reaction produces CO and/or C with H2O
  • Incomplete combustion gives carbon monoxide (CO) and water:
    2 C2H6 (g)+ 5 O2 (g) ===> 4 CO (g) + 6 H2O (g)

Halogenation: Substitution Reactions in Alkanes

  • UV light is required for reaction
  • one or more atom(s) of H is/are replaced by a halogen during reaction
  • The reaction is a three step process called the substitution mechanism
  • The steps are Initiation, Propagation, and Termination (see link for more details)